You have to hold this film up to the standards of very early 50s science fiction, which would be Rocketshp XM (also a Lippert production) and Destination Moon. This one already gets points for going the other way toward the center of the earth, and has both imagination (the "Cyclotram" is charming if absurd technology) and a different political bent (anti-war and anti-nuke, also like Rocketship XM in a way) than was acceptable then. It's different, fun, and memorable. Worth watching more than once.

I saw this in 1951 at the bottom of a double bill with Lash LaRue's "King Of The Bullwhip". Haven't seen it since until now. It would be viewed today as a fantasy/adventure with very little science and only the most fantastic and lurid fiction. Cheaply made in studio and at several outdoor locations which are supposed to double for the center of the earth or somewhere near there. If made today with color and computerized special effects available now it might be a shaggy dog of a different color, but it isn't. Low budget leading man Jim Bannon is in this for what it's worth. He's quite good. The rest of the cast including Victor Killian seem to be just going through the motions to get the film in the can.
Lippert Pictures by 1951 was parlaying small cheaply made pictures like this into a major distributorship replacing films that Republic, Columbia, Monogram and other "B" companies had either ceased to make or who had scaled back production due to costs and the erosion of audiences by television. The Lippert output was varied greatly in quality but usually watchable. Caution is advised.

Great sci-fi (heavy on the fi) period piece with some decent special effects, albeit on the cheesy side. Casting was pretty fair, script pretty formulaic, just a couple of rough spots/splices, but it'll keep most folks watching on a friday or saturday night until the popcorn runs out. Can't believe i missed this one when i was growing up.